Transforming the Industry: Digitalization and Automation in Oil and Gas Wells

*Rifaat Abdalla*

## **Abstract**

The oil and gas industry is undergoing a significant transformation with the advent of digitalization and automation technologies. This chapter explores the impact of digitalization and automation on drilling and completion operations in oil and gas wells. The integration of advanced technologies, such as artificial intelligence, machine learning, and robotics, has revolutionized the way wells are planned, drilled, and completed. Digitalization has enabled real-time data acquisition, analysis, and visualization, allowing operators to make informed decisions and optimize drilling and completion processes. Automated systems, including robotic drilling and remotely operated equipment, have enhanced operational efficiency, safety, and cost-effectiveness. The chapter discusses the implementation of digital twin models for virtual well planning and simulation, as well as the use of autonomous drilling systems and smart completion technologies. Moreover, the chapter addresses the challenges and opportunities associated with digitalization and automation, such as data security, workforce reskilling, and the need for collaboration across the industry. It emphasizes the potential for improved well performance, reduced environmental impact, and enhanced reservoir management through the integration of digitalization and automation in oil and gas wells.

**Keywords:** drilling techniques, completion methods, wellbore integrity, downhole tools, reservoir stimulation

## **1. Introduction**

## **1.1 Background and significance of digitalization and automation in the oil and gas industry**

The oil and gas industry has historically been characterized by its reliance on complex and capital-intensive operations. However, in recent years, digitalization and automation technologies have emerged as powerful catalysts for transformation within the industry. The integration of advanced technologies, such as artificial intelligence (AI), machine learning (ML), robotics, and data analytics, has opened up new possibilities for optimizing drilling and completion operations in oil and gas wells.

Digitalization refers to the use of digital technologies to collect, analyze, and interpret vast amounts of data in real time, enabling data-driven decision-making. Automation, on the other hand, involves the use of robotics, remote operations, and autonomous systems to perform tasks that were traditionally executed manually. These technological advancements have revolutionized the way wells are planned, drilled, and completed, resulting in improved operational efficiency, enhanced safety, and reduced costs.

### **1.2 Purpose and scope of the paper**

The purpose of this paper is to provide a comprehensive overview of digitalization and automation in the context of drilling and completion operations in the oil and gas industry. It aims to explore the impact of these technologies on well planning, drilling processes, completion techniques, and overall reservoir management.

The paper will delve into the various aspects of digitalization, including real-time data acquisition, data analytics, and the use of digital twin models for virtual well planning and simulation. It will also examine the different facets of automation, such as robotic drilling systems, remotely operated equipment, and autonomous drilling technologies.

Additionally, the paper will address the challenges and opportunities associated with the implementation of digitalization and automation in oil and gas wells. It will discuss issues such as data security, workforce reskilling, and the need for collaboration across the industry.

Through case studies and success stories, the paper will highlight tangible examples of how digitalization and automation have been successfully applied in the industry, showcasing the outcomes and benefits achieved. Finally, the paper will explore future trends and provide insights into the potential impacts and opportunities that lie ahead in this rapidly evolving field.

By examining the background, significance, purpose, and scope of digitalization and automation in the oil and gas industry, this paper sets the stage for a comprehensive exploration of the transformative role of these technologies in drilling and completion operations.

## **2. Digitalization in oil and gas wells**

### **2.1 Real-time data acquisition and monitoring**

In the era of digitalization, real-time data acquisition and monitoring play a crucial role in optimizing drilling and completion operations in oil and gas wells. This section focuses on the key components of real-time data acquisition, including sensors and data acquisition systems, data transmission and communication technologies, as well as real-time monitoring and visualization tools.

1.Sensors and Data Acquisition Systems: The deployment of advanced sensors is vital for capturing critical data during drilling and completion operations. These sensors are designed to measure various parameters such as temperature, pressure, flow rates, drilling parameters, and downhole conditions. The sensors are strategically placed in the wellbore, on drilling equipment, or integrated into completion tools to provide accurate and real-time data.

*Sensors commonly used in the oil and gas industry include:*


Data acquisition systems are responsible for collecting data from the sensors and transmitting it for further analysis and decision-making. These systems are designed to ensure accurate and reliable data capture, with capabilities for data integration and compatibility with other drilling and completion equipment.

	- Wired systems: Fiber optic cables or wired networks provide high-speed data transmission capabilities and are commonly used for onshore operations.
	- Wireless systems: Radio frequency (RF) communication, satellite communication, and cellular networks enable data transmission in offshore or remote locations. These wireless systems facilitate real-time data streaming from the sensors to the control centers.

The selection of appropriate data transmission technologies depends on factors such as the operational environment, distance, bandwidth requirements, and reliability.

	- Drilling control systems: These systems display real-time data such as rate of penetration (ROP), weight on bit, torque, and pump pressure. They also incorporate alarms and alerts to notify operators of any abnormal drilling conditions.
	- Data visualization software: These software applications process and display real-time data in a graphical format, facilitating data interpretation and

analysis. Graphs, charts, and 3D models can be generated to provide a clear understanding of well conditions and trends.

• Integrated operations centers: These centers bring together data from multiple sources, including sensors, drilling control systems, and production monitoring systems. They provide a centralized platform for real-time data monitoring, analysis, and collaborative decision-making.

Real-time monitoring and visualization tools empower operators and drilling engineers to identify potential issues, optimize drilling parameters, and improve overall drilling performance. These tools also contribute to enhanced safety and operational efficiency by enabling proactive responses to wellbore events and potential hazards.

By leveraging real-time data acquisition, transmission, and visualization tools, digitalization enhances the ability to monitor and respond promptly to changes.

## **2.2 Data analytics and decision-making**

Data analytics plays a vital role in harnessing the power of digitalization in oil and gas wells. This section focuses on the application of data analytics and its impact on decision-making in drilling and completion operations. It covers the use of artificial intelligence and machine learning, predictive analytics for drilling and completion optimization, and visualization techniques for data interpretation .

## 1.Artificial Intelligence and Machine Learning Applications

Artificial intelligence (AI) and machine learning (ML) techniques have revolutionized data analysis in the oil and gas industry. AI algorithms can process large volumes of data and identify patterns, correlations, and anomalies that may not be easily detectable by human analysis alone. Machine learning models can be trained using historical data to make predictions and recommendations based on real-time data inputs.

In drilling and completion operations, AI and ML applications are used for various purposes, including:


The use of AI and ML techniques in drilling and completion operations enables data-driven decision-making, enhances operational efficiency, and reduces risks. 2.Predictive Analytics for Drilling and Completion Optimization

Predictive analytics involves the application of statistical modeling and machine learning algorithms to historical and real-time data to forecast future drilling and completion outcomes. By analyzing vast datasets, predictive analytics can identify trends, optimize operational parameters, and anticipate potential problems.

In drilling and completion optimization, predictive analytics can be applied to:


By leveraging predictive analytics, drilling and completion operations can be optimized, risks can be mitigated, and operational efficiency can be significantly improved.

3.Visualization Techniques for Data Interpretation:

Visualization techniques play a crucial role in facilitating data interpretation and enabling effective decision-making. Visual representations of complex data provide insights and understanding that may not be apparent in raw numerical formats. Visualization techniques used in drilling and completion operations include:


By utilizing visualization techniques, drilling and completion professionals can quickly interpret data, identify patterns or anomalies, and make timely decisions to optimize operations and improve well performance.

It is worth to mention that the application of data analytics, including AI and ML, predictive analytics, and visualization techniques, empowers the oil and gas industry to extract valuable insights from vast amounts of data

4.Digital twin models for well planning and simulation

Digital twin models have emerged as powerful tools for well planning and simulation in the oil and gas industry. This section explores the concept and benefits of digital twins, as well as their applications in virtual well planning and optimization, and simulation and scenario analysis.

1.*Concept and Benefits of Digital Twins:*

A digital twin is a virtual replica of a physical asset or system, such as a well, that is continuously updated in real time using sensor data and other sources of information. It captures the physical, operational, and environmental characteristics of the asset, enabling a holistic view of its behavior and performance throughout its life cycle.

## *The benefits of digital twin models for well planning and simulation include:*


## 2.*Virtual Well Planning and Optimization:*

Digital twin models enable virtual well planning and optimization by simulating different drilling scenarios and evaluating their potential outcomes. By integrating data from various sources, including geological data, wellbore properties, drilling parameters, and environmental factors, digital twins provide a platform for engineers to analyze and optimize well designs before actual drilling operations commence.

## *Virtual well planning and optimization using digital twins involve:*

• Well placement analysis: Digital twins help determine the optimal location of wells within a reservoir by considering factors such as geology, fluid dynamics, and well interference.

*Transforming the Industry: Digitalization and Automation in Oil and Gas Wells DOI: http://dx.doi.org/10.5772/intechopen.112512*


Through virtual well planning and optimization, digital twin models enable engineers to identify the most efficient and cost-effective drilling approaches, leading to improved well performance.

## **3. Simulation and scenario analysis**

Digital twin models facilitate simulation and scenario analysis, allowing engineers to assess the impact of different variables and conditions on drilling and completion operations. By creating virtual environments that replicate real-world conditions, engineers can evaluate the behavior of the well under various scenarios and make informed decisions.

*Simulation and scenario analysis using digital twins involve:*


Simulation and scenario analysis using digital twin models provide valuable insights into the behavior of the well under different conditions, enabling proactive planning and risk management.

Digital twin models offer a holistic and real-time view of wells, enabling virtual well planning and optimization, as well as simulation and scenario analysis. By leveraging digital twins, operators and engineers can make informed decisions, optimize drilling operations, and mitigate risks, leading to improved well performance and operational efficiency.

## **4. Automation in oil and gas wells**

#### **4.1 Robotic drilling systems**

Automation has revolutionized the oil and gas industry, with robotic drilling systems playing a crucial role in improving operational efficiency and safety. This section focuses on the use of automated drilling equipment and robotics, highlighting their advantages and challenges.

1.*Automated Drilling Equipment and Robotics:*

Robotic drilling systems involve the use of advanced automation technologies and robotics to perform drilling operations. These systems aim to reduce human intervention, increase drilling efficiency, and enhance safety. Key components of robotic drilling systems include:


Robotic drilling systems offer several advantages over traditional drilling methods, but they also come with unique challenges that need to be addressed for successful implementation.

*Advantages of robotic drilling systems include:*


## *Challenges of robotic drilling systems include:*


Addressing these challenges through continuous research, development, and collaboration between industry stakeholders can pave the way for successful implementation of robotic drilling systems in oil and gas wells.

Robotic drilling systems offer numerous advantages, including increased efficiency, enhanced safety, and improved accuracy in oil and gas drilling operations. However, challenges such as technical complexities, adaptability, maintenance, and workforce reskilling need to be addressed to fully unlock the potential of automation in the industry.

	- 1.Case Study: Robotic Drilling in the North Sea: In the North Sea, an offshore drilling project utilized robotic drilling systems to improve operational efficiency and reduce costs. The project employed an automated drilling rig equipped with robotic arms and precise controls for handling drilling equipment and tubulars. The robotic system significantly reduced manual labor, enabling continuous drilling operations without shift changes. This resulted in a substantial increase in drilling efficiency and a significant reduction in drilling time. The use of robotics also enhanced safety by minimizing human exposure to hazardous drilling environments.
	- 2.Case Study: Autonomous Drilling Control in Unconventional Reservoirs: In unconventional reservoirs, such as shale formations, an oil and gas company implemented autonomous drilling control systems to optimize drilling operations. These systems utilized advanced algorithms and real-time data analysis to automate drilling parameter adjustments and detect drilling dysfunctions. By continuously monitoring and making precise adjustments to drilling

parameters, the autonomous control system improved drilling efficiency and reduced nonproductive time. The autonomous drilling control system also increased accuracy and precision in wellbore placement, leading to optimized reservoir targeting and improved production rates.

3.Case Study: Automated Pipe Handling in Onshore Drilling: An onshore drilling project incorporated automated pipe handling systems to streamline drilling operations. These systems utilized robotics to handle and position drill pipes, casings, and tubulars during drilling. The automated pipe handling systems reduced manual labor and minimized the risk of injuries associated with traditional pipe handling methods. The efficient and precise handling of tubulars resulted in faster and safer pipe connections, reducing nonproductive time and improving overall drilling efficiency.

These case studies demonstrate the successful implementation of robotic drilling applications in various drilling environments. The utilization of robotic systems, autonomous control, and automated pipe handling technologies has resulted in enhanced operational efficiency, improved safety, and optimized drilling outcomes. These advancements showcase the potential of robotic drilling in the oil and gas industry for increased productivity and cost-effectiveness.

## **4.2 Remotely operated equipment and systems**

Remotely operated equipment and systems have gained significant traction in the oil and gas industry, offering the ability to control and monitor operations from remote locations. This section focuses on the utilization of remote operation centers (ROCs), teleoperation, and remote control technologies and explores the benefits and limitations of remote operations.

1.Remote Operation Centers (ROCs): Remote operation centers (ROCs) serve as centralized hubs where drilling and production operations are monitored, controlled, and managed remotely. These centers leverage advanced communication technologies, data transmission systems, and real-time monitoring capabilities to enable remote oversight of well operations.

## *Key features and functions of ROCs include:*


*Transforming the Industry: Digitalization and Automation in Oil and Gas Wells DOI: http://dx.doi.org/10.5772/intechopen.112512*


Teleoperation and remote control technologies enable operators to control equipment and systems from remote locations, extending their reach to offshore or inaccessible areas. These technologies allow operators to remotely manipulate and operate equipment, leveraging high-speed communication networks and real-time video feeds.

*Key technologies used for teleoperation and remote control include:*


Remote operations offer several benefits to the oil and gas industry, but they also have limitations that need to be considered:

*Benefits of remote operations include:*


• Access to remote or hostile environments: Remote operations enable access to remote or hostile environments that are otherwise challenging or costly to reach. This includes offshore drilling platforms, subsea installations, or harsh environments like Arctic regions.

## *Limitations of remote operations include:*


## **4.3 Autonomous drilling systems**

Autonomous drilling systems have emerged as a transformative technology in the oil and gas industry, offering the potential for enhanced efficiency and safety. This section explores the components of autonomous drilling rigs, autonomous drilling operations, control algorithms, as well as safety considerations and regulatory aspects.

## 1.*Autonomous Drilling Rig Components:*

Autonomous drilling rigs are equipped with advanced technologies and components that enable them to operate with minimal human intervention. Key components of autonomous drilling rigs include:


2.*Autonomous Drilling Operations and Control Algorithms:*

Autonomous drilling operations involve the utilization of control algorithms and artificial intelligence (AI) to automate drilling processes and optimize performance. These algorithms continuously analyze real-time data and adjust drilling parameters to improve efficiency and accuracy.

*Key aspects of autonomous drilling operations and control algorithms include:*


## 3.*Safety Considerations and Regulatory Aspects:*

Safety considerations play a vital role in the development and deployment of autonomous drilling systems. The following aspects need to be addressed:


• Risk assessment and contingency planning: Rigorous risk assessments and contingency plans are necessary to address potential hazards and mitigate risks associated with autonomous drilling systems. This includes robust emergency response plans and well control procedures [2].

Safety considerations and regulatory aspects are critical to ensure the safe and responsible implementation of autonomous drilling systems, protecting personnel, assets, and the environment.

In summary, autonomous drilling systems integrate advanced components, control algorithms, and safety systems to enable drilling operations with minimal human intervention. These systems offer the potential for improved efficiency and accuracy.

## **5. Challenges and opportunities**

## **5.1 Data security and cybersecurity**

Data security and cybersecurity are critical concerns in the oil and gas industry, particularly with the increasing digitalization and connectivity of drilling and production operations. This section focuses on the challenges posed by data security and cybersecurity and explores strategies for protecting sensitive data and infrastructure from cyber threats.

## 1.*Protecting Sensitive Data and Infrastructure:*

With the adoption of digitalization and automation, vast amounts of data are generated and transmitted in real time throughout the drilling and production processes. Protecting this sensitive data and the infrastructure that supports it is crucial. Key considerations include:


2.*Cyber Threats and Mitigation Strategies:*

The oil and gas industry faces various cyber threats, including targeted attacks, malware, ransomware, and insider threats. Mitigating these threats requires a comprehensive approach. Key strategies include:


Addressing data security and cybersecurity challenges is essential to fully leverage the benefits of digitalization and automation in the oil and gas industry while protecting critical infrastructure and sensitive information.

In conclusion, data security and cybersecurity pose significant challenges in the oil and gas industry's digital transformation. Implementing robust security measures, including secure data storage and transmission, access controls, physical security, cybersecurity awareness, and incident response plans, helps protect sensitive data and infrastructure from cyber threats. By addressing these challenges, the industry can embrace digitalization and automation with confidence, unlocking the numerous opportunities they present for improved operational efficiency and performance.

## **5.2 Workforce reskilling and training**

The automation of oil and gas wells brings both challenges and opportunities for the workforce. This section explores the impact of automation on the workforce, the importance of upskilling and retraining programs, and the concept of humanmachine collaboration and evolving job roles.

## 1.*Impact of Automation on the Workforce:*

The introduction of automation in oil and gas wells can significantly transform job roles and tasks traditionally performed by the workforce. Some potential impacts include:


## 2.*Upskilling and Retraining Programs:*

To address the impact of automation on the workforce, upskilling and retraining programs are crucial. These programs help workers develop new skills and transition into roles that complement automation technologies. Key considerations include:


Rather than entirely replacing human workers, automation technologies often require collaboration between humans and machines. This collaboration can lead to the emergence of new job roles and responsibilities. Considerations include:

*Transforming the Industry: Digitalization and Automation in Oil and Gas Wells DOI: http://dx.doi.org/10.5772/intechopen.112512*


By implementing upskilling and retraining programs, organizations can empower their workforce to adapt to automation technologies, ensuring a smooth transition and maximizing the potential of human-machine collaboration.

In conclusion, automation in oil and gas wells brings changes to the workforce. Upskilling and retraining programs are crucial to equip workers with the necessary skills to complement automation technologies. Embracing human-machine collaboration and evolving job roles allows organizations to harness the benefits of automation while ensuring the workforce remains adaptable, competitive, and engaged [3].

## **5.3 Collaboration and industry-wide adoption**

Collaboration and industry-wide adoption are key factors in realizing the full potential of digitalization and automation in the oil and gas industry. This section explores the importance of data sharing and collaboration platforms, standardization efforts, and overcoming barriers to implementation.

## 1.*Data Sharing and Collaboration Platforms:*

Effective data sharing and collaboration platforms facilitate the exchange of information, experiences, and best practices among industry stakeholders. Key considerations include:


• Data ownership and privacy: Clear guidelines and agreements regarding data ownership, intellectual property, and privacy are crucial to build trust and encourage data sharing. Ensuring appropriate data protection measures are in place is essential to safeguard sensitive information.

## 2.*Standardization Efforts for Digitalization and Automation:*

Standardization plays a vital role in facilitating interoperability, compatibility, and seamless integration of digitalization and automation technologies. Key efforts include:


## 3.*Overcoming Barriers to Implementation:*

Despite the potential benefits of digitalization and automation, there are barriers to their widespread implementation. Overcoming these barriers is essential for industry-wide adoption. Key considerations include:


*Transforming the Industry: Digitalization and Automation in Oil and Gas Wells DOI: http://dx.doi.org/10.5772/intechopen.112512*

• Regulatory and policy frameworks: Regulatory and policy frameworks need to be adapted to accommodate the implementation of digitalization and automation technologies. Collaboration between industry stakeholders and regulatory bodies can help identify and address regulatory barriers.

By fostering collaboration, implementing industry-wide data sharing platforms, driving standardization efforts, and addressing barriers to implementation, the oil and gas industry can accelerate the adoption of digitalization and automation technologies.

In conclusion, collaboration and industry-wide adoption are crucial for the successful implementation of digitalization and automation in the oil and gas industry. Establishing data sharing and collaboration platforms, driving standardization efforts, and addressing barriers such as cost, change management, legacy systems, and regulations are key steps in unlocking the full potential of these technologies. Through collaborative efforts, the industry can drive innovation, improve operational efficiency, and create a sustainable future.

## **6. Case studies and success stories**

## **6.1 Examples of successful digitalization and automation projects**

Numerous successful digitalization and automation projects have been implemented in the oil and gas industry. Here are a few examples:


## **6.2 Key outcomes and benefits achieved**

The implementation of digitalization and automation projects in the oil and gas industry has yielded significant outcomes and benefits, including:


## **6.3 Lessons learned and best practices**

The successful implementation of digitalization and automation projects in the oil and gas industry has revealed valuable lessons and best practices, including:


By learning from these case studies, embracing best practices, and applying lessons learned, the oil and gas industry can further drive the successful implementation of digitalization and automation projects, leading to improved operational performance and sustainable growth.

## **7. Future trends and conclusion**

## **7.1 Emerging technologies and trends in digitalization and automation**

The future of digitalization and automation in the oil and gas industry is characterized by the emergence of several key technologies and trends. These include:


## **7.2 Potential impacts on the oil and gas industry**

The adoption of emerging technologies and the continued digitalization and automation of the oil and gas industry will have several potential impacts, including:


may be displaced, new roles will emerge that require advanced technical and analytical skills [5]. Workforce reskilling and upskilling programs will be critical to ensure a smooth transition.

4.**Integration of Digital Twins:** Digital twin models will become increasingly integrated into the planning and operations of oil and gas wells. This integration will enable real-time optimization, simulation, and scenario analysis for improved decision-making.

## **7.3 Summary of key findings and concluding remarks**

In summary, the digitalization and automation of oil and gas wells offer significant opportunities for the industry to enhance operational efficiency, improve safety, and drive sustainable practices. The successful implementation of these technologies requires collaboration, data sharing platforms, and standardized approaches.

Key findings include the importance of real-time data acquisition, advanced analytics, and automation in optimizing drilling and production operations. Digital twin models provide valuable insights for well planning and simulation, while automation technologies such as robotic drilling and remote operations offer improved efficiency and safety.

To fully harness the potential of digitalization and automation, the industry must address challenges such as data security, workforce reskilling, and regulatory frameworks. Collaboration, continuous learning, and a focus on innovation will be essential in navigating these challenges.

As the oil and gas industry moves forward, it must embrace emerging technologies, adapt to changing workforce dynamics, and drive industry-wide adoption. By doing so, the industry can position itself for continued success, resilience, and sustainability in the future.

## **Author details**

Rifaat Abdalla Department of Earth Sciences, College of Sciences, Sultan Qaboos University, Oman

\*Address all correspondence to: rabdalla@squ.edu.om

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Transforming the Industry: Digitalization and Automation in Oil and Gas Wells DOI: http://dx.doi.org/10.5772/intechopen.112512*

## **References**

[1] Smith JA, Johnson BR. Intelligent operations. Journal of Petroleum Technology. 2022. Available from: https://jpt.spe.org/intelligentoperations-2022 [Accessed: May 26, 2023]

[2] Robinson M. Intelligent well completion. In: Petroleum Engineering Handbook (PEH). 2023. ISBN 978-1-55563-122-2

[3] Novakova L. The impact of technology development on the future of the labour market in the Slovak Republic. Technology in Society. 2020;**62**. ISSN 0160-791X. DOI: 10.1016/j. techsoc.2020.101256

[4] Hegde G, Gray K. Evaluation of coupled machine learning models for drilling optimization. Journal of Natural Gas Science and Engineering. 2018;**56**:397-407. ISSN 1875-5100. DOI: 10.1016/j.jngse.2018.06.006

[5] Tassey G. Standardization in technology-based markets. Research Policy. 2000;**29**(4-5):587-602. ISSN 0048-7333. DOI: 10.1016/ S0048-7333(99)00091-8

## **Chapter 4**

## Casing While Drilling

*Siraj Bhatkar and Vinayak Wadgaonkar*

## **Abstract**

Conventional drilling methods have faced significant operational and financial challenges, such as the cost of purchasing, inspecting, handling, and transporting drill equipment, and, most importantly, tripping in and out of the drill string whenever the Bottom Hole Assembly (BHA) requires replacement, a wiper trip, or total depth is reached. Tripping the drill string in and out not only contributes to Non Productive Time (NPT), but also causes well control issues such as wellbore instability and lost circulation. All of this has prompted the oil and gas sector, as well as any other engineering industry, to look for innovative techniques and approaches to address these issues. A new drilling method has emerged as a result of technological developments and continuous improvements to conventional drilling methods. Casing when drilling has been established as a result of technological developments and continuous improvements to traditional drilling processes. Casing Drilling is the process of drilling and casing a well at the same time, employing active casing to maximize production. This paper provides an overview of the casing while drilling method (CwD) and its practical application in well drilling. The typical drilling method and casing while drilling are also compared. The CwD approach outperforms the standard drilling method by a wide margin.

**Keywords:** casing, drilling, non productive time, bottom hole assembly, casing while drilling

## **1. Introduction**

The rising need for and reliance on energy resources by mankind, especially those brought on by the discovery and exploitation of new commercial hydrocarbon deposits, entails the utilization of innovative innovations, such as drilling process optimization by lowering the expenses, the hazards, and the wasted time. While drilling, casing while drilling replacing traditional drilling string with casing string both to circulate and to transmit mechanical energy to the bit a well is being drilled with fluid. Casing while drilling has a lot of technical and cultural obstacles to overcome, but the significant advantages of this technology—such as shorter drilling times and fewer issues with the drilling string—make it a more and more attractive option to traditional drilling. Experience with using this technology has shown that it can speed up well execution and, occasionally, lower expenses relative to drilling depth.

According to data from the International Energy Agency [1], the world's natural gas demand has been rising steadily since 2009, reaching 3757 billion m3, with the potential to climb to a 23–25% share of the world's energy consumption by 2040.

Since natural gas is the primary fuel substitute for coal in the electricity generation industry, despite the higher risks associated with the explosive nature of natural gases, the world's increased demand for this fuel is primarily due to its lower environmental impact when compared to other fossil fuels, particularly with regard to air quality and greenhouse gas emissions [2]. Accordingly, 22% of the world's electricity supply in 2014 was made up of natural gas. This may vary from 17 to 32% by 2060, representing a 300–1500 bcm absolute increase [3].

Gas producers develop drilling programs for both production and exploration in order to meet this demand. Production drilling aims to boost the rate of gas production from existing reservoirs. Exploration drilling seeks to find new gas sources [4]. Due to difficulties and technological mishaps that may occur during drilling that may increase the wells' final cost, sizeable sums are frequently allotted to achieve such investment plans. However, these sums are frequently wasted before the program is completed [5]. More and more businesses experiment with and use novel drilling techniques and technology that decrease downtime, mitigate risk, and prevent technical mishaps during drilling in an effort to lower such unanticipated expenses of well drilling operations. Casing while drilling, also known as CwD (Continuous Bottom hole Pressure), Pressurized Mud Cap Drilling, and Dual Gradient Drilling, are alternatives to controlled pressure drilling [6]. Casing while drilling is an alternative to standard drilling that involves drilling the well and casing it at the same time [7].

Even though the casing while drilling method was developed in the 1920s, widespread use wasn't conceivable until the last 10 years as a result of technical developments [4, 8]. By minimizing drilling time and issues with the drilling string, the strategy was therefore shown to be successful in lowering overall drilling costs.

#### **1.1 The tools for casing while drilling**

Casing during drilling can be done with either standard drilling rigs that require little additional equipment or drilling rigs that are specifically designed for this usage.

The drilling rig, which consists of the three vital systems of drive, rotary, and circulation, must achieve the principal parameters of the drilling regime and consolidation of the well bore [9]. The conventional links are operated remotely in order to remove the derrick man from the monkey board, and the surface casing drive systems have been modified and improved to allow for casing while drilling. This allows the casing to be run in the hole, the drilling fluid to be circulated, and the casing to rotate safely on the derrick in place of the conventional tongs.

Surface Casing Drive Systems (**Figure 1**) can be used for a wide range of casing sizes because they can be automatically controlled by PLC from the driller cabin and can be externally clamped for small casings (from 3 12 in to 9 5/8 in) or internally clamped for casing larger than 9 5/8 in.

Casing while drilling can be done primarily in two ways:


In order to drill by rotating the casing from the surface, which eliminated the ability to remove the bit, it was necessary to develop specialized drilling bits that had

comparable performance to normal bits. Since they are simple to mill with PDC bits after cementing, these may act as casing shoes once the appropriate depth has been reached—**Figure 2**.

In order to cement immediately after hitting TD, a float collar is typically installed within the casing while drilling.

The steel float collar (**Figure 3**) almost matches the resistance of the casing, and its valve must withstand drilling fluid erosion as well as pump pressure and pressure from the casing itself. The casing is fitted with centralizers to keep the well on track, to control casing wear, and to line the casing up during cementing (**Figure 4**). During directional drilling with casing, it is advised to utilize centralizers with rough surfaces and robust, non-rotating blades made of zinc alloy since they are incredibly durable (see **Figure 5**).

In order to accommodate the unique operating circumstances in the well, casing threads are different from those used for traditional drilling. As a result, the casing makers created a variety of casings to address the difficulties and harsh well conditions that emerged during casing while drilling. These connections must guarantee fatigue resistance, sufficient sealing capability, and torque resistance [10].

**Figure 2.** *Milling the drilling bit used for CwD.*

When casing while drilling, it may be necessary to use a recoverable/retractable drilling system since damaged equipment must be replaced before the casing depth is reached.

In order to retrieve the costly drilling equipment used for a directional casing, operators must quickly and effectively reach the formations beneath the casing shoe.

A bottom hole assembly (BHA), which can be inserted into and removed by a wireline, is used for drilling while casing. Its basic components are a bit and an under reamer *Casing While Drilling DOI: http://dx.doi.org/10.5772/intechopen.113889*

at the bottom of the casing string to drill a hole large enough to allow the casing to pass freely. The BHA is placed in a nipple at the lower end of the casing string that can be retrieved by wireline without removing the casing from the well and is attached to a Drill-Lock Assembly (DLA) engaging axial lock and torsional lock. The releasable DLA transfers compression and torque loading while rotating the drilling and casing strings. It is advised to apply centralizers on the casing to stop sleeves from wearing out [11].

## **2. CwD benefits**

Many issues with traditional drilling are eliminated or much diminished by using CwD. One significant category of these issues is brought on by the drilling string, which poses the following risks:


Another set of issues related to installing casing in wells with bent or collapsed holes can be avoided by doing it while drilling. Additionally, difficulties brought on by crossing unstable formations (borehole collapsing and over pull), crossing formations with loss of circulation, or crossing formations that have deteriorated from prolonged contact with drilling fluids can all be avoided [12].

These problems are solved by the so-called plastering effect, which is produced by spinning the casing string in a small annular region, sealing the formation pores, and fortifying the borehole walls.

According to **Figure 6**, while drilling with a standard drilling string, the annular gap is bigger. By using casing during drilling, the annular space is reduced to a minimum, creating a wellbore that is more stable and sealed. Furthermore, the stiffness of the casing string creates a less convoluted hole, lowering the possibility of key seats or mechanical sticking, and the high annular rising velocity of the drilling fluid via this annular region enhances debris cleaning from the wellbore.

By removing the time and effort required for casing string tripping, CwD also has the advantage of reducing drilling time overall. Since the float collar was inserted before drilling began, the drilling fluid is changed with cement once the casingsetting depth has been reached. For this reason, operations such as control tripping of the borehole to correct over pulling areas, circulating to remove solids from the fluid, performing electrometric operations, retrieving the bit by decomposing strings, and inserting casing by filling the casing string at each casing section are avoided [13].

**Figure 6.** *Annular space size in conventional drilling vs. casing while drilling.*

## **2.1 Problems with the CwD casing design**

A steel casing that is bolted together for CwD boreholes strengthens the casing design concerns. The commonly utilized casing is 6–12 m long, with diameters of 4–20 in, and wall thicknesses of 5–15 mm.

The goal of casing a well is to: -


Tensile force, compression, outer and inner pressure, and gravity are the forces affecting the casing string (see **Figure 7**). Additional forces (fatigue, torque, and buckling) act on the casing when drilling because of it. In order to determine the profile of a casing, the strength of the casing to these forces must be understood.

The weight of the casing itself causes tensile force to exist. These will snap at the weakest area if the tensile force exceeds a critical level, which is equal to the tensile strength of the casing.

Given that the tensile strength of the casing's connection is different from the strength of the casing body, the calculation must be performed for both components in order to take into account the lowest values when determining the casing profile. The fluid behind the casing's hydrostatic column provides the majority of the outside pressure.

When the pressure exceeds the strength of the casing, the casing may collapse. We must take into account the relationship between the nominal diameter D and wall thickness t in order to calculate the critical pressure for casing made in accordance with API regulations. The ratio (thick wall casing) determines the outer pressure that is exerted on the inner casing wall at the minimal yield point.

The cutting action, as well as the friction of the casing against the borehole wall and/ or the previously cased hole, result in torque at the drill bit at the bottom of the hole.

**Figure 7.** *Forces acting on the casing.*

Since the drill bit is above the bottom hole, the only source of torque is casing friction. Due to friction forces operating on the point where the borehole walls and casing make contact, the torque applied to the casing during drilling is typically larger than during traditional drilling, resulting in a strength moment whose vector direction is the opposite of the casing's rotation. Thus, the moment at the bit is substantially lower than the rotating moment at the surface when the casing is rotating in the borehole and exerting a certain weight on the bit [14].

The cyclic load at various stress levels that are significantly below the material's yield point causes fatigue. A minor fracture begins to grow from the high-stress point along the casing and eventually breaks it under sustained strain.

It becomes unstable due to buckling, which is caused by the bending moments produced by the geometry of the casing borehole and the compressive stress. If the casing is subjected to compressive stress that is greater than a specific threshold, the casing buckles into a sinusoidal or helical pattern.

Following buckling, the casing leans on the borehole walls; as a result, the lateral force from the point of contact may produce wear and raise the moment needed for rotation [15].

The casing string must be sized in stages, taking into account the factors mentioned above:


The following additional loadings must be taken into account:


It is necessary to use safety coefficients during the design phase to execute casing while drilling under safe settings. Tensile forces should be given the strongest safety coefficients possible in order to account for additional stress caused by things like buckling, dynamic forces, sticking trends, and friction with the borehole wall. For the upper joint of the casing, a safety factor of 1.6 to 1.8 is used in relation to tension. The calculation hypotheses for such stress are less likely to be realized when the coefficient for breaking and crushing is smaller, for breaking 1.1 and 1.0, and for crushing 0.9.

## **3. Casing while drilling-related safety issues versus traditional drilling**

Risk is the possibility of an occurrence that could be advantageous or detrimental to a project or activity. It can be defined as a combination of the likelihood that the risk will

## *Casing While Drilling DOI: http://dx.doi.org/10.5772/intechopen.113889*

materialize and the implications of loss or gain. As a result, hazards can be divided into four categories: low, medium, high, and very high. The methodical process of locating, evaluating, and reacting to a project's possible risks is known as risk management [16].

Drilling risks may be caused by geology, technical-operational problems, or a mix of the two while a project is being carried out. The so-called difficult geological formations are characterized by the physical and chemical properties of the rocks through which the borehole passes and by the properties of fluids contained in pores or fractures; subjective challenges are related to technology and method. In terms of projects, all risks are identified, risk exposure is evaluated by calculating the likelihood of occurrence and the impact, and then such risks are avoided or managed by putting in place an effective risk management system. The primary dangers that could arise during conventional drilling are depicted on maps in **Tables 1** and **2**. Or during drilling, casing. Each project's risk occurrence likelihood is individually estimated based on correlation wells, drilling technology, and techniques. Comparing the two tables leads to the conclusion that drilling with casing could result in a reduction or minimize drilling-related hazards, particularly those relating to traditional drilling string, to preserve circulation loss or borehole stability [17].


#### **Table 1.**

*Drilling cost comparison between conventional drilling and CwD for vertical well.*


#### **Table 2.**

*Capital equipment cost required to convert conventional drilling rig into CwD rig.*

*Advances in Oil and Gas Well Engineering*

## **Author details**

Siraj Bhatkar\* and Vinayak Wadgaonkar Department of Petroleum Engineering, MIT-World Peace University, Pune, India

\*Address all correspondence to: siraj.bhatkar@mitwpu.edu.in

© 2024 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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## **Chapter 5**
